In a sign that smaller deals are also subject to increased scrutiny by antitrust regulators, the Federal Trade Commission sued risk and credit report provider Dun & Bradstreet Corporation on Friday, challenging its February 2009 purchase of Quality Education Data (QED), valued at just $29 million.

At the time, only deals larger than $65 million required antitrust clearance. That threshold was reduced earlier this year to around $63 million. In March, the Justice Department ordered voting machine company Election Systems & Software Inc. to partly unwind its closed $5 million transaction to purchase a Diebold Inc. unit.

Quality Education sells data about K-12 school districts. According to the complaint, a Dun & Bradstreet unit sells similar information, and the merger gave the company more than 90 percent of the market for K-12 educational marketing databases.

“When Dun & Bradstreet acquired QED, it bought its closest competitor and created a monopoly,” FTC competition bureau director Richard Feinstein said in a statement. ”That’s going to get the FTC’s attention every time.”

“D&B believes we have not violated any antitrust laws as a result of our acquisition of QED,” a company spokeswoman said in a statement. “We are in the process of trying to resolve this issue with the Federal Trade Commission.”